Modern mobile communications tend to increasingly provide users with multimedia services with high-speed transmission. FIG. 1 illustrates a system architecture diagram of SAE (System Architecture Evolution). In FIG. 1, a UE (User Equipment) 101 is a terminal apparatus for receiving data. An E-UTRAN (Evolved UMTS Terrestrial Radio Access Network) 102 is a radio access network comprising a macro base station (enhanced Node B (eNodeB) or Node B) for providing the UE with interfaces to access to radio networks. An MME (Mobility Management Entity) 103 is responsible for managing mobile contexts, session contexts and security information of the UE. An SGW (Serving Gateway) 104 mainly provides a function of user plane, and the MME 103 and the SGW 104 may be located in the same physical entity. A PGW (Packet Data Network Gateway) 105 is responsible for functions such as billing, legally interception and etc. The PGW 105 and SGW 104 may also be located in the same physical entity. A PCRF (Policy charging and rules function) 106 provides QoS (Quality of Service) strategies and charging rules. An SGSN (Serving GPRS Support Node) 108 is a network node apparatus for providing data routing in a UMTS (Universal Mobile Telecommunications System). An HSS (Home Subscriber Server) 109 is a home ownership subsystem of the UE and is responsible for protecting user equipment information, such as current location of the user equipment, addresses of the service nodes, user equipment security information and packet data contexts of the user equipment.
In 3GPP release 12 (Rel-12), requirements for small cell enhancement are put forwarded, wherein objective scenarios of the small cell enhancement comprises scenarios with macro-cell coverage and without macro-cell coverage, enhancement for indoor and outdoor, ideal backhaul and non-ideal backhaul, as shown in FIG. 2. In FIG. 2, F1 and F2 correspond to different frequency points, respectively.
In the case of having macro-cell coverage, a technology for applying inter-NodeB CA (Carrier Aggregation) is provided. The macro cell and the small cell may work on different frequency bands. There are two types of architecture for applying the inter-NodeB CA technology: an architecture of user plane data being split based on RAN (Radio Access Network) and an architecture of user plane data being split based on CN (Core Network). In the architecture of user plane data being split based on CN, for a bearer set up on a pico cell (Pico cell), data is transmitted directly from the SGW of CN to the pico cell, and the user plane data cannot be forwarded through the macro cell.
In the architecture of small cell, the UE may transmit/receive data simultaneously from two base stations, which is referred to as a dual-connectivity. Only one of the two base stations is responsible for transmitting an RRC (Radio Resource Control) message to the UE and responsible for interactivity with the MME which is a control plane entity of the CN, and thus the base station is referred to as a master base station (Master eNB, MeNB), while the other is referred to as a secondary base station (Secondary eNB, SeNB). One cell in the master base station is a primary cell of the UE (Pcell), through which the RRC messages is transmitted to the UE; while the other cells are secondary cells (Scells). One cell of the UE among the Scells in the secondary base station is a primary cell of secondary base station (pScell). The pScell has an uplink physical layer control channel (UPCCH), whereas other Scell has no UPCCH. A cell group of the master base station is an MCG (Master Cell Group), and the cell group of the secondary base station is a SCG (Secondary Cell Group). Resources of the SCG of the UE are configured by the secondary base station, wherein the configuration for the UE is transmitted by the secondary base station to the master base station via an RRC container, and then transmitted by the master base station to the UE. The master base station does not parse the RRC container, or parse it without modifying the configurations of the RRC container.